Recently, many wireless devices having wireless interfaces based on IEEE802.11 standard have been commercialized and become available. Most of wireless communication apparatuses having the wireless interfaces based on IEEE802.11 standard provide high portability, and are often used in portable devices. Most of portable devices are driven by a battery, and it is, therefore, important to reduce battery consumption.
The IEEE802.11 standard defines a power management specification to intermittently execute transmission and reception using the fact that an actual communication time is discontinuous even when a wireless interface is effective. A power management function based on IEEE802.11 standard includes an active mode in which data can always be received, and a power save mode in which data can be received only under a specific condition. The IEEE802.11 standard defines an infrastructure mode in which a wireless communication apparatus (station) communicates with another wireless communication apparatus via an access point serving as a base station, and an ad hoc mode in which stations communicate with each other. Note that the power save mode is disclosed in Japanese Patent Laid-Open No. 2003-348095.
A large difference between the infrastructure mode and ad hoc mode in power management is as follows. In the infrastructure mode, an access point is always a communication partner of the station and is always in the active mode. Hence, the station can transmit data without consideration of the power management state of the communication partner (access point). To the contrary, in the ad hoc mode, a station serving as the communication partner may be in the power save mode. Therefore, data must always be transmitted while considering whether the partner is in the active mode or power save mode. Accordingly, processing becomes complex.
As has been described above, a power management function in the ad hoc mode is complex, and has not been installed in a product. However, it is anticipated that the power management function will be installed in various products hereinafter. If the product having the power management function in the ad hoc mode appears on the market, many wireless communication apparatuses will communicate with each other in the power save mode state in an ad hoc network. However, when a wireless communication apparatus (to be referred to as a new apparatus hereinafter) having no power management function in the ad hoc mode joins the ad hoc network in which wireless communication is executed in the power save mode state, the following problems are posed.
For example, since the new apparatus which newly joins the ad hoc network has no power management function, the new apparatus is always in the active mode, and performs communication by regarding the partner as the wireless communication apparatus in the active mode. Hence, the partner wireless communication apparatus in the power save mode cannot receive data from the new apparatus.
The present invention has been made in consideration of the above situation, and has as its object to provide a communication apparatus, control method, and program therefore which can prevent data download error when the communication apparatus newly joins a network in a power save mode.